Index: trunk/src/org/openstreetmap/josm/gui/history/HistoryBrowserModel.java
===================================================================
--- trunk/src/org/openstreetmap/josm/gui/history/HistoryBrowserModel.java	(revision 4565)
+++ trunk/src/org/openstreetmap/josm/gui/history/HistoryBrowserModel.java	(revision 4566)
@@ -596,4 +596,6 @@
         @Override
         public int getRowCount() {
+            // Match the size of the opposite table so comparison is less confusing.
+            // (scroll bars lines up properly, etc.)
             int n = 0;
             if (current != null && current.getType().equals(OsmPrimitiveType.RELATION)) {
@@ -644,5 +646,5 @@
             if (relation == null)
                 return null;
-            if (row >= relation.getNumMembers())
+            if (row >= relation.getNumMembers()) // see getRowCount
                 return null;
             return relation.getMembers().get(row);
Index: trunk/src/org/openstreetmap/josm/gui/history/NodeListTableCellRenderer.java
===================================================================
--- trunk/src/org/openstreetmap/josm/gui/history/NodeListTableCellRenderer.java	(revision 4565)
+++ trunk/src/org/openstreetmap/josm/gui/history/NodeListTableCellRenderer.java	(revision 4566)
@@ -62,8 +62,7 @@
     }
 
+    // Warning: The model pads with null-rows to match the size of the opposite table. 'value' could be null
     public Component getTableCellRendererComponent(JTable table, Object value, boolean isSelected, boolean hasFocus,
             int row, int column) {
-        if (value == null)
-            return this;
 
         renderNode((TwoColumnDiff.Item)value, isSelected);
Index: trunk/src/org/openstreetmap/josm/gui/history/RelationMemberListTableCellRenderer.java
===================================================================
--- trunk/src/org/openstreetmap/josm/gui/history/RelationMemberListTableCellRenderer.java	(revision 4565)
+++ trunk/src/org/openstreetmap/josm/gui/history/RelationMemberListTableCellRenderer.java	(revision 4566)
@@ -92,8 +92,7 @@
     }
 
+    // Warning: The model pads with null-rows to match the size of the opposite table. 'value' could be null
     public Component getTableCellRendererComponent(JTable table, Object value, boolean isSelected, boolean hasFocus,
             int row, int column) {
-        if (value == null)
-            return this;
 
         HistoryBrowserModel.RelationMemberTableModel model = gteRelationMemberTableModel(table);